Trench header duct system



Sept. 29, 1970 E. H. CARTER ETAL 3,530,627

TRENCH HEADERDUCT SYSTEM 7 .4 Sheets-Sheet 1 Filed July 10, 1968 INVENTORS [ass/vs r4. Carers/z flLBERrC WHEELER E. H. CARTER ET AL TRENCH HEADER DUCT SYSTEM Sept; 29, 1970 .4 Sheets-Sheet 2 Filed- July 10, 1968 n 4 IIIIII'IIIJ "III :NYENTOR.

EUGENE (/mrzz flLee/er C. #4 55452 W W firm/ave Y Sept. 29, 1970 CARTER ETAL 3,530,627

TRENCH HEADER DUCT SYSTEM 14 Sheets-Sheet 5 Filed July 10, 1968 aiii m m M )q from/5 V Sept. 29, 1970 CARTER ETAL TRENCH HEADER DUCT SYSTEM .4 Sheet-Sheet 4.

Filed July 10, 1968 I NVENTORS 6 Cxmrze 141.59%? C Wl/EELER s N s w 5 q Tram/Er United States Patent 3,530,627 TRENCH HEADER DUCT SYSTEM Eugene H. Carter, Bellevue, and Albert C. Wheeler,

Seattle, Wash., assignors to General Electric Company,

a corporation of New York Filed July 10, 1968, Ser. No. 743,776 Int. Cl. E0411 /48; E04f 19/0-8; H02g 3/12 US. Cl. 52-221 13 Claims ABSTRACT OF THE DISCLOSURE A trench header duct system complete with straight length sections and the following sub-assemblies compatible therewith: elbow, T, cross, and end cap assemblies, up-elbow, cabinet riser and connecting flange, and expansion joints; the straight length sections each including a U-shaped duct trough, a pair of cover support angles adjustably supported on respective opposed side wall portions of the duct trough, a pair of screeding and anchoring angles supported in juxtaposed relation to the cover support angles, and a cover having trim portions in perpendicular relation thereon wherein the cover is reversible between a screeding position in which the cover trim portions are in abutting relation with the cover support angles and a finished position in which the flat bottom surface of the cover is in substantial abutting relation with the cover support angles.

BACKGROUND OF THE INVENTION Field of the invention Our invention relates to electrical wiring duct systems, and more particularly to an improvement in a trench header duct system of the type intended to be employed in conjunction with either metal cellular flooring for building construction or underfloor electrical wire distribution means associated with buildings having reinforced concrete flooring.

Description of the prior art In accordance with the prior art, it has become commonplaced in large buildings having concrete or other similar floor construction to employ an underfloor wiring distribution system to wire the floors in order to provide electrical service where necessary. One way of accomplishing this involves the use of a network of ducts installed under the floor such that the ducts comprise passages wherein electrical wiring may be installed. Because the parallel cells of multi-cellular flooring lend themselves to being utilized as passages for the wires, such flooring is particularly adapted for use in such distribution systems. To provide a means whereby wires may be led from one cell to another of the multi-cellular floor ing, trench header ducts are commonly positioned on top of the multi-cellular flooring in juxtaposed perpendicular relation thereto.

For satisfactory performance it has been found that there are several structural features which a trench header duct should be provided with irrespective of whether the duct is intended to be employed in conjunction with a reinforced concrete floor or in conjunction with a metal cellular floor covered with a layer of concrete of predetermined thickness. The first of these features is one which is necessitated by virtue of the fact that it is very diflicult to lay a concrete floor so as to have a top surface which is completely level throughout. For this reason, it has been found desirable to provide trench header duets with some form of adjustment means whereby at least the top surface, i.e., cover plate, of the duct may be adjusted relative to the top surface of the concrete floor.

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A variety of different ways of providing this adjustment have been tried by the prior art but none of them have proven to be entirely satisfactory. For example, in some forms of trench header duct the side walls have been of two-part construction whereby with the cover plate of the duct secured to the uppermost part of the respective side walls, the uppermost part of the side wall with the cover plate attached thereto may be adjusted in a vertical plane relative to the respective lower part of each of the side walls. Another approach has been to provide the trench header duct with means whereby the cover plate thereof may be adjusted to a limited degree relative to the side walls of the duct which are each of one-piece construction. Finally, some use has been made of the idea of utilizing side walls having a two-part construction whereby the respective parts of each of the side walls are adjustable in a vertical plane relative to each other, while at the same time providing additional means in the trench header duct whereby the cover plate itself is adjustable relative to the uppermost part of the two-part side walls.

One of the inherent problems encountered in employing trench header ducts which have side Walls that are of two-part construction is that on the one hand the respective parts of each of the side walls must be freely movable so that they may be adjusted relative to each other, while on the other hand the spacing therebetween must be sufficiently small such as to prevent any of the concrete which is poured around the sides of the trench header duct from entering the duct to thereby cause corrosion therein, etc. Most prior art forms of trench header duct having two-part side wall construction are characterized by the fact that they all permit a certain amount of concrete to enter the interior of a the duct.

Where the side walls are each integral, i.e., of onepiece construction, and the trench header duct is provided with other means for adjusting the cover plate relative to the side walls, such means most commonly comprising essentially nothing more than a rotatable screw type arrangement, two basic problems have existed. One is that in some of these trench header ducts the screw-like member is not enclosed within the interior of the duct but rather extends outwardly thereof whereby when concrete is poured around the duct screw-like member is also covered with concrete with the result that subsequent operation of the screw-like member becomes very diflicult if not impossible. The other is that the sole support for the cover plate when the latter having been adjusted to the floor level is spaced from the side walls is the screw-like member itself. In this condition should any substantial load be placed on the cover plate, it has been found that the screw-like member will incur damage often times to the extent that subsequent operation thereof is inhibited.

OBJECTS OF THE INVENTION It is an object of the present invention to provide an improved trench header duct system which has side walls which permits vertical adjustment of the cover plate supported thereon while at the same time preventing concrete poured therearound from entering the interior of the trench header duct system.

It is another object of the present invention to provide such a trench header duct system having in addition a screw-like adjustment means for the cover plate which is inaccessible to concrete and which enables the cover plate to support substantial loads without the screw-type adjust ment means suffering any damage.

A still further object of the present invention is to provide such a trench header duct system having two-part side 3 wall construction and additional screw-type adjustment means for the cover plate which system may be employed in conjunction with a reinforced concrete floor or in conjunction with a metal cellular floor which is subsequently covered with a layer of concrete of predetermined thickness.

Still another object of the invention is to provide elbow assemblies, end cap assemblies and expansion joints that are adapted to simply cooperate with the trench header duct.

Yet another object of the present invention is to provide such an improved trench header duct system which is simple in construction, easy to install, and relatively inexpensive to manufacture.

SUMMARY OF THE INVENTION In accordance with one aspect of the present invention there is provided a trench header duct including a substantially U-shaped duct having a base and a pair of opposed side walls. A cover support member is supported in juxtaposed relation to each of the opposed side walls of the duct. A first adjustment means is provided to permit the cover support members to slide vertically relative to the corresponding side walls of the U-shaped duct. A screeding and anchoring member is mounted in juxtaposed relation to each of the cover support members and is movable therewith relative to the corresponding duct side walls. To close the open top of the U-shaped duct a cover plate is provided having a substantially flat portion and trim portions extending outwardly on at least two sides of the fiat portion in substantially perpendicular relation thereto. A second adjustment means supports the cover plate on the cover support members such that the cover plate is invertible between a first position in which the trim portions of the cover plate are in abutting relation to the cover support members and second position in which the fiat portion of the cover plate is in abutting relation to the cover support members. The cover plate is vertically adjustable by either or both of the first and second adjustment means whereby the cover plate may be made flush with a given level of floor.

In accordance 'with another aspect of this invention an elbow assembly and up-elbow assembly are provided having flanged portions to facilitate attachment to the trench header duct in a minimum time and expense.

In accordance with another aspect of this invention and end cap assembly is provided having means for attaching to the trench header duct and means for adjusting the height of the cap to maintain abutment relation to the finished floor in a minimum. time and expense.

lIn accordance with another aspect of this invention an expansion joint is provided having portions adapted to facilitate simple attachment to the trench header duct in a minimum time and expense.

The invention will be more fully understood from the following detailed description and its scope will be pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a plan view of a section of trench header duct which forms a part of a trench header duct system in accordance 'with the present invention;

(FIG. 2 is a sectional view of the trench header duct of FIG. 1 illustrating the various elements thereof in the position they occupy when in the screeding position;

FIG. 3 is a sectional view of the trench header duct of FIG. 1 similar to FIG. 2 but illustrating the position of the elements thereof when in the finished position;

FIG. 4 is a perspective View of an elbow assembly employable with a trench header duct system in accordance with the present invention;

FIG. 5 is a perspective view of an end cap assembly illustrated as being associated with a portion of a trench header duct of a trench header duct system in accordance with the present invention, some parts being broken away for purposes of clarity of illustration;

FIG. 6 is a perspective view of an up-elbow assem: bly illustrated in association with a portion of a trench header duct of a trench header duct system in accordance with the present invention, some parts being broken away for purposes of clarity of illustration;

FIG. 7 is a perspective view of a cabinet riser and connection flange employable with the up-el'bow assembly of FIG. 6 in accordance with the present invention; and

FIG. 8 is a perspective view of an expansion joint employable with a trench header duct system in accordance with the present invention.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring to FIGS. 1, 2 and 3 of the drawings, the invention is shown as incorporated in a trench header duct system 10 including a trench header duct 11 which includes a U-shaped duct trough 12 having a base 13 and a pair of upwardly extending opposed side walls 14 and 15. Slidably supported in juxtaposed relation to the outer surface 14a and 15a, respectively, of each of the side walls 14 and 15 are L-shaped cover support angles 16 and 17 having leg portions 16a, 16b, and 17a, 17b5, respectively. The cover support angles 16 and 17 as well as the side walls 14 and 15 are each suitably provided with elongated openings (not shown) which are provided for the purpose of receiving screws 18 which preferably are employed with loclewashers 19 to secure the aforesaid memlbers together in a manner to be more fully set forth hereinafter.

Each of a pair of L-shaped screeding and anchoring angles 20 and 21 having leg portions 20a, 20b, and 21a, 2112, respectively, is mounted with the respective leg portion 20a and 21a thereof in juxtaposed relation to the leg portion 16a and 17a of the cover support angles 16 and 17, respectively. This is accomplished by means of the aforesaid screws 18 which are received in suitable opening (not shown) provided in the respective leg portions 20a and 21a of the angles 20 and 21. The screws 18 are threaded into openings (not shown) suitably provided in the aligning strips 22 and 23, the latter having leg portions 22a, 22b, and 23a, 23b, respectively, each pair of which extend substantially at right angles to each other. With the screws 18 threaded therein, the strips 22 and 23 are positioned such that the leg portions 22a and 23a thereof are in juxtaposed relation to the leg portions 20a and 21a respectively of the screeding and anchoring angles 20 and 21, while the leg portions 22b and 23b of the aligning strips 22 and 23 rest on the leg portions 20b and 21b of the angles 20 and 21 in abutting relation thereto.

The top side of the U-shaped duct trough 12, i.e., the side opposite the base 13, is closed by means of a series of substantially flat cover plates 24, each having a pair of trim portions 25 and 26 fixed by any suitable means to opposite edge portions of the plates 24 such that the trim portions 25 and 26 extend outwardly therefrom in the same given direction and are substantially perpendicular to the cover plate edge portions whereby each of the cover plates 24 is provided with a tray-like configuration along one surface thereof.

With reference to FIGS. 2 and 3 of the drawings, it is seen that the cover plates 24 are invertible between a first or screeding position and a second or finished position. In the screeding position as shown in FIG. 2, the flat surface of the cover plate 24 is uppermost and the trim portions 25 and 26 in juxtaposed relation to the leg portions 16b and 17b of cover support angles 16 and 17, respectively. To detachably secure the cover plates 24 in the screeding position, a plurality of screws 27 are employed each of which passes through an opening suitably provided therefor in the cover plate 24 and threadedly engages a tapped opening (not shown) located in the corresponding leg portion 16b and 17b of the cover support angles 16 and .17, respectively. Screeding filler strips 28 are utilized to fill the spaces otherwise existing between the screeding and anchoring angles 20 and 21 and the trim portions 25 and 26. In the preferred embodiment of the invention, the length of each of the screeding filler strips 28 is substantially equal to that of the associated cover plate 24.

As illustrated in FIG. 3, when the cover plates 24 are in the finished position, the tray-like configurations formed along one surface thereof are uppermost while the bottom surface of each of the plates 24 is supported in slightly spaced relation to the cover support angles 16 and 17. Strips 29 and 30 of suitable gasketing material are positioned respectively along the bottom surface of the cover plates 24 at each end thereof and along the underside of the trim portions 25 and 26.

In accordance with the invention, the screeding filler strips 28 are replaced by finish angles 31 when the cover plates 24 are placed in the position referred to previously as the finished position. The finish angles 31 which are substantially L-shaped in configuration have leg portions 31a and 31b extending in substantially perpendicular relation to each other. When in place, the leg portion 31b of finish angle 31 is supported such that one surface thereof is in juxtaposed relation to the corresponding leg portion 16b and 17b of cover support angles 16 and 17, respectively, while the other surface thereof is in abutting relation to the strip 30 of gasketing material. Leg portion 31a of the finish angles 31 which is of the same height as the trim portions 25 and 26 occupies the space between one of the trim portions 25 and 26 and the corresponding screeding and anchoring angles 20 and 21.

Flat-headed screws 33 are utilized to secure the cover plates 24 in the finished position. The screws 33 pass through the same openings in the cover plates 24 and the cover support angles 16 and 17 previously referred to in connection with the description of the manner in which screws 27 are employed to secure the cover plates 24 in the screeding position. In addition however each of the flat-headed screws 33 passes through an opening suitably provided in a gusset 34 which is positioned within the tray-like configuration at the uppermost surface as viewed in FIG. 3 of the cover plates 24 preferably at each of the four corners thereof. The gusset 34 is also provided with a recessed portion adjacent the screw opening therein whereby the flat head of screw 33 when positioned therein is flush with the top surface of the gusset 34. Each of the screws 33 is threaded into a nut 35 carried by the cover gasket support member 36 preferably in fixed relation thereto. As illustrated in FIG. 3, the cover gasket support member 36 which may be provided with a reinforcing rib 36a extends transversely across the width of the dust trough 12 between the cover support angles 16 and 17 for the purpose of supporting the strip 29 of gasketing material and the portion of the cover plate 24 thereabove, and also providing a securing means for the screws 33. It will be noted that each end 36b of the cover gasket support member 36 is offset downwardly to a sufiicient extent with respect to the main portion thereof so as to provide room for the nut 35 carried thereby as well as for the thickness of the leg portions 16b and 17b of cover support angles 16 and 17, respectively positioned thereabove.

For the purposes of the following description of the manner in which trench header duct is installed, it is relatively immaterial whether the trench header duct 11 is being employed in conjunction with a reinforced concrete flooring or in conjunction with a metallic multicellular flooring which is to be covered with a layer of concrete of predetermined thickness other than to note that in the case of the latter the duct 11 is laid on top of the multi-cellular flooring with the base 13 of the duct 11 extending in perpendicular relation thereto whereas in the case of the former the duct 11 is laid so as to extend in whatever direction is preferable. It is of course understood that when the duct 11 is utilized with multicellular flooring the base 13 threof is provided with a plurality of suitable openings (not shown) arranged so as to be capable of being aligned with corresponding openings in the multi-cellular flooring for the purpose of providing access thereto in a manner well known to those skilled in the art.

Thus with the base 13 of the trench header duct 11 laid flat relative to one or the other of the aforesaid two types of flooring, the cover plate 24 is placed in the screeding position as illustrated in FIG. 2 of the drawings, and is secured in this position by means of the screws 27 in the manner previously described. Screws 18 are then loosened so that the cover support angles 16 and 17 along with the cover plate 24 and the screeding and anchoring angles 20 and 21 associated therewith may be adjusted in a vertical plane relative to the side walls 14 and 15 of the U-shaped duct trough 12 to the desired level, i.e., the level which corresponds to the desired height of the concrete poured therearound. The screws 18 are then retightened. With reference to FIG. 2, it will be noted that the upper edge portions of the screeding and anchoring angles 20 and 21 and the screeding filler strips 28 as well as those of the cover plate 24 and the trim portions 25 and 26 fixed thereto present a flush surface whereby no portion thereof extends above the screeding level which otherwise might be damaged by virtue of the passage thereover of wheelbarrows, carts, etc. carrying concrete or other equipment utilized in the pouring of the concrete therearound. One of the functions of the leg portions 2% and 21b of the screeding and anchoring angles 20 and 21 which extend outwardly of the side walls 14 and 15 in substantially perpendicular relation thereto is to provide a means whereby after the concrete hardens the duct 11 is locked into the surrounding concrete fill. It should also be noted that inasmuch as adjoiningsections of the trench header duct 11 are aligned and tied together by means of the tie and aligning strips 22 and 23, the entire length of the duct 11 as well as each individual section thereof becomes locked into the surrounding concrete fill after the concrete hardens.

After the concrete surrounding the trench header duct 11 has hardened, the screws 27, the cover plate 24 and the screeding filler strips 28 are each removed. The filler strips 28 are then replaced by the finish angles 31, the latter being positioned on the cover support angles 16 and 17 with their respective leg portions 31b in juxtaposed relation to the leg portions 16b and 17b of cover support angles 16 and 17, respectively, and with their leg portions 31a in juxtaposed relation to the inner surface of the corresponding leg portions 20a and 21a of the screeding and anchoring angles 20 and 21. The strip 30 of gasketing material is then positioned on the leg portion 31b of finish angle 31 in abutting relation thereto. Similarly the strips 29 of gasketing material are positioned so that they will be in abutting relation with the under surface of cover plate 24 at each end thereof. A notched cover gasket support member 36 isbifurcated to retain a plurality of captive nuts. The cover gasket support member is positioned under and in abutment with cover support angles 16 and 17. The cover plate 24 with the gussets 34 and screws 33 thereon is placed on the cover support angles 16 and 17 in supporting relation thereto and with the screws 33 passing through the openings provided therefor in the cover support angles 16 and 17. The screws 33 are then threaded into the captive nuts 35 carried by the previously positioned cover gasket support member 36. The screws 33 are thereafter tightened to the extent necessary so as to compensate for any unevenness in the surrounding concrete surface which might have occurred as the result of additional sag in the building floor stemming from the added weight of the concrete.

The screws 33 thus in effect provide an additional adjustment means.

With reference to FIG. 3 it will be noted that the fiat heads of screws 33 are flush with the top surface of the gussets 34 and that the latter are flush with the upper edges of trim portions 25 and 26 and finish angles 31. In addition it will be noted that the top surface of cover plate 24 corresponds in height to the upper edge portions of the screeding and anchoring angles 20 and 21 which is lower than that of the gussets 34, etc. by a predetermined amount. The difference in height allows room for a layer of linoleum, etc. of comparable thickness to be placed over the surrounding concrete surface as well as within the tray-like configuration present on the upper surface as viewed in FIG. 3 of cover plate 24. The installation and use of such a cover layer of linoleum, etc. is well known to those skilled in the art.

In accordance with the preferred embodiment of the invention and as illustrated in FIG. 1 of the drawings, the top surface of each section of trench header duct 11 is provided with a plurality of cover plates 24 arranged in end-to-end relation. Thus for example, for a ten foot length of trench header duct there might be utilized therewith a total of five cover plates 24 each having a twofoot length. The duct 11 is thereby provided with cover plates 24 any one of which may be removed at any point and cover plates 24 which in addition by virtue of their comparatively small size are easily manageable so as to facilitate the lay-in of cables, etc. within the U-shaped duct trough 12 as well as the subsequent servicing thereof.

In addition as shown in FIG. 3 of the drawings, in some installations it is desirable that the interior of U- shaped duct trough 12 be divided up longitudinally into a pair of separate compartments or that vertical deflection of cover plate 24 under load be minimized. This may be accomplished by utilizing a pair of elongated substantially L-shaped barrier members 37 and 38, each having leg portions 37a and 37b, 38a and 38b, respectively. To install the barrier members 37 and 38, leg portion 37a of barrier member 37 is first secured to the base 13 at the desired location by suitable means such as welding, etc. The barrier members 37 and 38 are fastened together by means of screws 39 which pass through elongated openings (not shown) suitably provided in the leg portions 37b and 38b of barrier members 37 and 38, respectively. The screws 39 thread into nuts 40 and preferably a lockwasher 41 is utilized with each of the screws 39. It will thus be noted that inasmuch as the screws 39 when loosened may be moved in the aforesaid elongated openings the barrier members 37 and 38 may be adjusted in a vertical plane relative to each other so that their height corresponds substantially to that of the cover support angles 16 and 17. Preferably a strip 42 of suitable gasketing material is employed on the top surface of leg portion 38a of barrier member 38. The strip 42 engages the inner surface of the cover plate 24 when the latter is secured to the cover support angles 16 and 17 in the finished position thereby providing a tight seal therebetween and in conjunction with the other strips 29 and 30' of gasketing material precluding the entrance of moisture and other contaminants into the interior of the duct trough 12.

Referring to FIG. 4 of the drawings, there is illustrated therein a horizontal elbow assembly, designated generally by the reference numeral 43, which comprises another aspect of the present invention. The elbow assembly 43 is compatible with straight length sections of trench header duct 11 and provides a means of changing the direction of the duct 11 as is oftentimes required in order to provide electrical service to a particular location in a given installation.

The horizontal elbow assembly 43 includes an essentially square base plate 44 which is provided at each of its respective corners with a punched hole 45 through which the corner posts 46 extend, the latter being perferably welded in place. In addition the base plate 44 in accordance with the preferred embodiment of the invention is provided with a total of twelve tapped openings 47, three of which are provided along each edge portion of the base 44 for a purpose to be more fully set forth hereinafter. An essentially square filler plate 48 of smaller dimension than the base plate 44, which is posi tioned on the base plate 44 serves to eliminate uneveness and shap edges of adjoining sections of trench header duct 11 with which the elbow assembly 43 is associated when used in a given installation. It will be noted with reference to FIG. 4 of the drawings that the filler plate 48 is provided with notches 48a at each of its corners in order to provide clearance for the corner posts 46 which extend upwardly from the base plate 44 in substantially perpendicular relation thereto. The corner posts 46 by virtue of the cooperation therewith of the notched portions 48a of filler plate 48 serve to properly position as well as retain the filler plate 48 on the base plate 44. Further, the corner posts 46 position and brace the adjoining sections of duct 11 with which the elbow assembly 43 is associated as well as the side wall assemblies of the elbow assembly 43 itself, and also provide a smooth rounded edge to protect cables or wires, etc. which may be located within the duct 11 and the elbow assembly 43. Finally the corner posts 46 may also serve as a caulking stop or gasket retainer if desired.

Referring further to FIG. 4 of the drawings, wall angles 49 and 50 extend along two sides of the elbow assembly 43 and have their respective leg portions 49a and 50a secured to the base plate 44 in overlying relation thereto and in substantially abutting relation to edge portions of the filler plate 48 by means of screws 51 threaded into appropriate ones of the previously described openings 47. Cover support angles 52 and 53 which are similar to those previously described in connection with the trench header duct 11 of FIGS. 2 and 3 are supported with their respective leg portions 52a and 53a in juxtaposed relation to the leg portions 49b and 50b of wall angles 49 and 50, respectively. Screws 54 which pass through elongated openings (not shown) suitably provided in the wall angles 49 and 50 and the cover support angles 52 and 53 are utilized for the purpose of securing the wall angle 49 to the cover support angle 52 and the wall angle 50 to the cover support angle 53. Preferably a lockwasher (not shown) is employed with each of the screws 54. The screws 54 also serve to fasten the screeding and anchoring angles 55 and 56 to the cover support angles 49 and 50 with the leg portions 55a and 56a of the screeding and anchoring angles 55 and 56, respectively, in juxtaposed relation to the leg portions 52a and 53a of the cover support angles 52 and 53, respectively. It should be noted that by loosening the screws 54, the cover support angles 52 and 53 and the screeding and anchoring angles 55 and 56 supported thereon may be adjusted in a vertical plane relative to the wall angles 49 and 50, the extent of vertical adjustment being limited essentially only by the length of the aforesaid elongated openings in which the screws 54 are received.

Cut-out portions 520 and 53c, respectively, are provvided at opposite ends of the leg portions 52b and 53b, respectively, of the cover support angles 52 and 53. Underlying the cut-out portions 520 and 530 at the interior of the corner at which the cover support angles 52 and 53 meet is a right angle cover hold-down strip 57 which has its leg portion 57a secured to te leg portion 52b of cover support angle 52 by suitable means such as screws 58. The leg portion 57b of the cover hold-down strip 57 is similarly secured to leg portion 53b of cover support angle 53 preferably by means of a pair of the aforesaid screws 58. The cover hold-down strip 57 is also provided with a threaded opening 570 centrally located therein for the purpose of receiving one of the screws utilized in securing in place the member similar in construction to that of the cover plate 24 which serves as a cover for the elbow assembly 43. Adjacent each of the cut-out portions 52c and 530 located at the other end of the respective leg portions 52b and 53b of the corner support angles 52 and 53 there is provided a cover holddown strip designated by reference numerals 59 and 60 respectively. End portions 59a and 60a of the aforesaid cover hlod-down strips 59 and 60 are fastened by means of screws 61 to thecorresponding leg portions 52b and 53b of the cover support angles 52 and 53. The other end portion, i.e., that designated by reference numerals 59b and 6012 respectively of cover hold-down strips 59 and 60 is offset upwardly to a suflicient extent such that its upper surface lies in substantially the same horizontal plane as the leg portions 52b and 53b of cover support angles 52 and 53. The cover hold-down strips 59 and 60 as in the case of cover hold-down strip 57 are also provided with a threaded opening 59C and 60C respectively capable of receiving one of the screws utilized in securing the cover member of elbow assembly 43 in place.

Although not shown in FIG. 4 in the interest of clarity of illustration in accordance wtih the preferred embodiment of the invention a finish angle (not shown) similar to that designated by reference numeral 31 in FIG. 3 would be interposed between the leg portions 55a and 56a of screeding and anchoring angles 55 and 56 and the edge portions of the cover member for elbow assembly 43. Likewise it should be understood that a strip of suitable gasketing material similar to the strip 30 previously described in connection with the structure of trench header duct 11 shown in FIG. 3 of the drawings would be positioned in substantially overlying relation to each of the legs 31b of the finish angle 31.

The respective side wall assemblies of the elbow assembly 43 are interconnected to adjoining sections of trench header duct 11 by means of tie and aligning straps 62 and 63, each of which has one of its ends, i.e., that designated by reference numeral 62a, fastened by means of one of the screws 54 previously described hereinabove to the corresponding leg portion 55a and 56a of screeding and anchoring angles 55 and 56. Although not specifically i1 lustrated in the drawings the other end portion of each of the tie and aligning straps 62 and 63 would be suitably fastened to one of the screeding and anchoring angles of the adjoining section of trench header duct 11. Finally a right angle tie and aligning strap 64 is utilized in a similar fashion for the purpose of interconnecting the two adjoining sections of trench header duct 11 associated with the elbow assembly 43. Suitable threaded openings 64a and 64b capable of receiving fastening means such as screws (not shown) are provided for this purpose in the tie and aligning strap 64. Also it is to be understood that suitable cover gasket support members and cooperating strips of gasketing material similar to those designated in FIG. 3 of the drawings by reference numerals 36 and 29, respectively, would preferably be employed at least adjacent each of the open sided portions of the elbow assembly 43. That is, the aforesaid cover gasket support members would extend transversely between pairs of corner posts 46 and adjacent thereto.

Because of the standardization which exists between all of the various parts which comprise the side wall assemblies of the elbow assembly 43, it is possible simply by removing or adding parts to change the elbow assembly 43 into a T or Cross assembly which includes the Wall angle 49, the cover support angle 52, and screeding and anchoring angle 55, along with the cover hold-down strip 57, and substituting a right angle tie and aligning strap similar to that designated by reference numeral 64 in FIG. 4 of the drawings for the tie and aligning strap 62, it is possible to convert the elbow assembly 43 into a T assembly wherein sections of trench header duct 11 could be connected to three sides of the assembly. In addition of course it would be necessary to provide another elongated tie and aligning strap extending outwardly from the end of the screeding and anchoring angle 56 opposite that from which the tie and aligning strap 63 extends and another cover hold-down strip similar to 60. Similarly to convert the aforesaid T assembly to a Cross assembly essentially all that would be required would be to omit the remaining side wall assembly along with the tie and aligning strap 63 and provide two additional right angle tie and aligning straps simlar to that designated by reference numeral 64 whereby there would be one such right angle tie and aligning strap located adjacent each of the four corner posts 46. With a cross assembly it is therefore possible to interconnect four adjoining sections of trench header duct 11 at right angles to each other.

Referring now to FIG. 5 of the drawings, there is illustrated therein another aspect of the present invention which comprises an end cap assembly, generally designated by the reference numeral 65, which is utilized as a means of closing off the end of a given length of trench header duct 11. The end cap assembly 65 includes a bottom plate 66 upon which rests the base 13 of U-shaped duct trough 12 in substantially abutting relation to the end angle 67, the latter having a leg portion 67a mounted by suitable means on the bottom plate 66 and a leg portion 67b extending upwardly as viewed in FIG. 5 from the bottom plate 66 in perpendicular relation thereto.

Cover support angle 68 is slidably mounted on the end angle 67 with its leg portion 68a in juxtaposed relation to the leg portion 67b of end angle 67. Cover support angle 68 as well as end angle 67 are provided with elongated openings capable of receiving a screw 69 which is preferably empolyed with a lockwasher and nut (not shown) for the purpose of fastening the end angle 67 and the cover support angle '68 together. The screw 69 also serves to mount the elongated end plate 70 in juxtaposed relation to the leg portion 68a of cover support angle 68.

As seen in FIG. 5 of the drawings, end plate 70 at either end thereof is attached to the respective side wall assemblies of a standard section of trench header duct 11 by means of right-angled mounting brackets 71 which each have a leg 71a fastened by suitable means such as screws 72 to the corresponding cover suport angles 20 and the other leg 71b thereof fastened to a shim 73 also by suitable means such as screws 74 which are threaded into tapped openings suitably positioned in brackets 71. The screws 74 also pass through suitable openings provided in end plate 70 and cover support angle 68 whereby the latter are all fixedly secured together by means of the screws 74. In addition the uppermost ones of the screws 74 as viewed with reference to FIG. 5 of the drawings pass through filler strip 75 which is thereby mounted in juxtaposed relation to a portion of the inner surface of end plate 70 and such that one of its edge portions is in abutting relation to leg portion 68b of cover support angle 68 and the other edge portion of the filler strip 75 is flush with the upper edge of the end plate 70.

With reference further to FIG. 5 of the drawings, the opposite ends of leg portion 68b of cover support angle 68 are provided with notches 680 to provide room for the respective ends of the leg portions of cover support angles 16 which comprise respective parts of the side wall assemblies of the standard section of trench header duct 11 with which the end cap assembly 65 is associated. Underlying leg portion 68b of cover support angles 16 are right-angled cover hold-down strips 76, the latter being secured to leg portion 68b by means of screws 77. The cover hold-down strips 76 are each provided with a centrally located opening which is aligned with an opening 78 in each of cover support angles 16 for the purpose of receiving one of the screws (not shown) which is used to secure in place the cover plate 24 of trench header duct 11. Although not illustrated in FIG. 5 of the drawings, it will be understood that the end cap assembly 65 and standard section of trench header duct 11 are preferably provided with suitable strips of gasketing material similar to those designated by reference numerals 29 and 30 in FIG. 2. A further point to note is that by loosening screw 69 the cover support angle 68 and end plate 70 mounted thereon may be adjusted in a vertical plane relative to the end angle 67 of end cap assembly 65 whereby the latter may be positioned such that the upper edge of end plate 70 is at substantially the same level as the upper edge of the screeding and anchoring angles 20 and 21 of trench header duct 11.

Referring now to FIG. 6 of the drawings, there is illustrated therein another aspect of the present invention which comprises an up-elbow assembly, generally designated by the reference numeral 79, which is employed when it is desired to change the direction of the trench header duct 11 from horizontal to vertical to enable for example the cables, wire, etc. housed in the duct 11 to be fed to a wall-mounted cabinet for connection therein. The up-elbow assembly 79 which is intended to be compatible with a standard section of trench header duct 11 includes a bottom plate 80 upon which rests the base 13 of U-shaped duct trough 12 of trench header duct 11. The end of base 13 is positioned in abutting relation to side wall 81a of L-shaped end angle 81, the other wall 81b of end angle 81 being fixedly secured to bottom plate 80 by suitable means such as by welding, etc.

End plate 82 is slidably supported on end angle 81 by means of screws 83 which are received in elongate-d openings (not shown) in end angle 81 and end plate 82. The screws 83 are threaded into L-shaped nuts 84. Interposed between end plate 82 and mounting brackets 85, the latter being similar to the L-shaped mounting brackets 71 previously described in connection with the end cap assembly 65 of FIG. 5, are a pair of shims 86. The mounting brackets 85 each have one end 85a suitably secured to a shim 86 and the other end 85b fastened by means of screw 87 and L-shaped nut 88 to corresponding screeding and anchoring angles 20 and 21 of a standard section of trench header duct 11.

As further seen with reference to FIG. 6 of the drawings, the vertical portion of the up-elbow assembly 79 comprises a U-shaped throat member 89 having an end wall 89a supported on end plate 82 by means of screws 90 threaded into tapped openings suitably provided in the end plate, while the opposed side walls 89b and 890 of member 89 are positioned in juxtaposed relation to the cover support angles 16 and 17 of trench header duct 11. The front wall of the U-shaped throat member 89 is closed by means of an L-shaped cover support angle 91 having a side wall 91a which is of the same height as the side walls of the member 89 and which is fastened by means of screws 92 to the flange portions 89d and 89a of side walls 89b and 890, respectively. The leg portion 91b of cover hold-down angle 91 is fastened by suitable means such as screws 93 to an elongated cover hold-down strip 94 which extends transversely across the top of the trench header duct 11. Although not shown in FIG. 6 of the drawings in the interest of clarity of illustration, it is to be understood that the up-elbow assembly 79 and the standard section of trench header duct 11 associated therewith preferably are provided with suitable strips of gasketing material similar to those designated by reference numerals 29 and 30, the use of which have been previously described in connection with FIGS. 2 and 3 of the drawings. Further, it should be noted that the up-elbow assembly 79 is also vertically adjustable in the same manner as that previously described in connection with the end cap assembly 65 of FIG. of the drawings.

In FIG. 7 of the drawings, there is illustrated a cabinet riser 95 and a connection flange 96 which are used in conjunction with the up-elbow assembly 79 of FIG. 6 in a manner to be more fully set forth hereinafter. The cabinet riser 95 comprises an essentially U-shaped member 97 having a side wall 97a, and opposed end walls 9% and 970 from which inwardly extend flange portions 97d and 97e. The overall inside dimensioins of the U-shaped member 97 are slightly greater than the outside dimensions of the U-shaped throat member 89 of up-elbow assembly 79 such that in use the member 97 may be slid over throat member 89. The open side wall of the member 97 is closed by means of a riser front 98 which consists of an elongated flat metallic member which is fastened by means of a plurality of screws 99 to the flange portions 97d and 97e of member 97.

The connection flange 96 as illustrated in FIG. 7 is U-shaped in construction with flanges 96a, 96b, 96c extending outwardly from the respective side walls thereof. In use, the connection flange 96-is slipped into the interior of U-shaped member 97 such that the flange portions 96a, 96b, and 960 are substantially resting on the upper edge portionsof the side and end walls of U-shaped member 97 and with the holes 100 in the opposed side walls of the connection flange 96 aligned with openings 101 suitably provided in end walls 97b and 97c of member 97 whereby suitable means such as screws (not shown) may be' received in the aforesaid openings for the purpose of securing the connection flange 96 and the member 97 together. In addition, an elongated member 102 having notched edge portions 102a, and a plurality of screw openings 103 therein is positioned within the U-shaped member 96 in juxtaposed relation to the side wall 97a of member 97 and with the openings 103 in alignment with the openings 104 suitably provided in side wall 97a of member 97 whereby the notched portions 102a of member 102 rest on flange portions 96a and 96c of connection flange 96. With the member 102 suitably secured to side wall 97a of member 97 by means of screws (not shown) which are received in the aforesaid openings 103 and 104, the member 102 by virtue of the cooperation between the notched portions 102a thereof and the flange portions 96a and 96c serves to further hold the connection flange 96 in place on the cabinet riser 95. The upper three holes 105 provided in the member 102 as viewed with reference to FIG. 7 of the drawings are intended to be utilized to secure the cabinet riser 95 with connection flange 96 attached thereto to a wall-mounted cabinet (not shown) by suitable means such as screws, etc.

A final component of the trench header duct system which is the subject matter of the instant invention is an expansion joint, which is generally designated by reference numeral 106 in FIG. 8 of the drawings. The expansion joint 106 is intended to be employed between adjoining sections of trench header duct 11 for the purpose of providing a means whereby the ends of the aforesaid sections of duct may be adjusted relative to each other in what is normally a substantially horizontal plane.

The expansion joint 106 includes a U-shaped trough 107 which is similar to the duct trough 12 of trench header duct 11 but has slightly smaller outside dimensions such that the trough 107 may be slid within the adjoining sections of trench header duct 11. A side angle 108 is adjustably mounted on each of the side walls 107a and 107b, respectively, of trough 107 by means of screws 109 which pass through elongated openings 110 provided in the side walls 107a and 1071; of trough 107 and are received in tapped openings suitably provided in the side angles 108. A cover 111 which extends transversely between the side angles 108 is provided for the purpose of closing the otherwise open top wall of the trough 107. The cover 111 is secured to the leg portions 108a of each of the side angles 108 by suitable means such as screws 112 threaded into tapped openings suitably provided therefor in the side angles 108. In accordance with the preferred embodiment of the invention strips of gasketing material are provided along the opposed edge portions 111a and 111b of the cover 111 in order to provide a tight seal between the cover 111 and the side angles 108. To employ the expansion joint 106 in a trench header duct system essentially all that is required is that the trough 107 with side angles 108 and cover 111 mounted thereon in the manner described hereinabove be slid into the interior of the U-shaped duct troughs 12 of two adjoining standard sections of trench header duct 11. The side angles 108 of expansion joint 106 would of course be adjusted vertically relative to the side walls 107a and '7b of trough 107 by means of screws 109 so as to correspond substantially in height to that of the cover support angles 16 and 17 of the sections trench header duct 11 with which the expansion joint 106 is associated.

In accordance with our invention and as set forth hereinabove, we have provided a trench header duct system which includes a straight length or standard section of duct, elbow, T, cross, and end cap assemblies, an up-elbow assembly, a cabinet riser and connection flange, and an expansion joint. Our trench header duct system includes side walls which are vertically adjustable to correspond to the desired floor level of the concrete poured thereon, but yet side walls which prevent any concrete from entering into the interior of the trench header duct system. Our trench header duct system further includes a cover plate which is invertible between a screending position in which it is flush with the desired screeding level and a finished position in which the trim portions carried thereby are flush with a cover layer of linoleum, etc. The cover plate is also independently adjustable after the surrounding concrete floor has been poured by means of rotatable screw means which are constructed so as to minimize the chances of their being damaged by virtue of the cover plate being required to withstand appreciable loads. Finally, we have provided a trench header duct system which is employable in conjunction with a reinforced concrete floor or in con junction with a metal cellular floor which is subsequently covered with a layer of concrete of predetermined thickness, but yet a trench header duct system in which all of the various components thereof are characterized by the fact that they are relatively simple in construction, relatively easy to install, and relatively inexpensive to manufacture.

While we have disclosed only one embodiment of our invention, it will be appreciated that many modifications thereof may readily be made by those skilled in the art, and we therefore intend by the appended claims to cover all such modifications as fall within the true spirit and scope of our invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. A trench header duct comprising:

(a) an elongated duct trough having a base and a pair of opposed side walls extending outwardly from said base in perpendicular relation thereto;

(b) a pair of cover support angles, each of said pair of cover support angles including first and second leg portions extending in perpendicular relation to each other;

(c) a pair of screeding and anchoring angles, each of said pair of screeding and anchoring angles including first and second leg portions extending in perpendicular relation to each other;

(d) first means supporting said first leg portion of each of said pair of cover support angles in juxtaposed relation to one of said pair of opposed side walls of said duct trough and said first leg portion of each of said pair of screeding and anchoring angles in juxtaposed relation to one of said first leg portions of said pair of cover support angles;

(e) a plurality of cover plates, each of said plurality of cover plates having a flat portion and trim portion in perpendicular relation; and

(f) second means supporting said plurality of cover plates on said second leg portions of said pair of cover support angles wherein each of said plurality of cover plates is invertible between a screeding position wherein said trim portions are in abutting relation with said second leg portions of said pair of cover support angles and a finished position wherein said trim portions extend outwardly away from said second leg portions of said pair of cover support angles.

2. A trench header duct as set forth in claim 1 wherein said second means supporting said plurality of cover plates on said second leg portions of said pair of cover support angles includes adjustment means for individually adjusting each of said plurality of cover plates relative to said second leg portions of said pair of cover support angles.

3. A trench header duct as set forth in claim 2 further comprising:

(a) a first barrier member having first and second leg portions extending in perpendicular relation to each other;

(b) means fixedly supporting said first leg portion of said first barrier member on said base of said duct trough;

(c) a second barrier member having first and second leg portions extending in perpendicular relation to each other; and

(d) adjustment means supporting said first leg portion of said second barrier member for movement in juxtaposed relation to said second leg portion of said first barrier member.

4. A trench header duct comprising:

(a) an elongated duct trough having a base and a pair of opposed side walls extending outwardly from said base in perpendicular relation thereto;

(b) a pair of cover support angles, each of said pair of cover support angles including first and second leg portions extending in perpendicular relation to each other;

(c) first adjustment means supporting said first leg portion of each of said pair of cover support angles for movement in juxtaposed relation to one of said pair of opposed side walls of said duct trough;

(d) a plurality of cover plates, each of said plurality of cover plates having a flat portion and trim portion mounted along at least two edges of said flat portion in perpendicular relation thereto;

(e) means supporting said plurality of cover plates on said second leg portions of said pair of cover support angles wherein each of said plurality of cover plates is invertible between a screeding position wherein said trim portions are in abutting relation with said second leg portions of said pair of cover support angles and a finished position wherein said trim portions extend outwardly away from said second leg portions of said pair of cover support angles;

(f) said cover plate supporting means including second adjustment means for individually adjusting each of said plurality of cover plates relative to said second leg portions of said pair of cover support angles;

(g) a pair of screeding and anchoring angles, each of said pair of screeding and anchoring angles including first and second leg portions extending in perpendicular relation to each other, said first leg portion of each of said pair of screeding and anchoring angles being supported in juxtaposed relation to one of said first leg portions of said pair of cover support angles; and

(h) a pair of elongated filler strips supported in said second leg portions of said pair of cover support angles in abutting relation to said first leg portions of said pair of screeding and anchoring angles and one of said plurality of cover plates when said one of said plurality of cover plates is in said screeding position.

5. A trench header duct comprising:

(a) an elongated duct trough having a base and a pair of opposed side walls extending outwardly from said base in perpendicular relation thereto;

(b) a pair of cover support angles, each of said pair of cover support angles including first and second leg portions extending in perpendicular relation to each other;

(c) first adjustment means supporting said first leg portion of each of said pair of cover support angles for movement in juxtaposed relation to one of said pair of opposed side walls of said duct trough;

(d) a plurality of cover plates, each of said plurality of cover plates having a flat portion and trim portion mounted along at least two edges of said flat portion in perpendicular relation thereto;

(e) means supporting said plurality of cover plates on said second leg portions of said pair of cover support angles wherein each of said plurality of cover plates is invertible between a screeding position wherein said trim portions are in abutting relation with said second leg portions of said pair of cover support angles and a finished position wherein said trim portions extend outwardly away from said second leg portions of said pair of cover support angles;

(f) said cover plate supporting means including second adjustment means for individually adjusting each of said plurality of cover plates relative to said second leg portions of said pair of cover support angles;

(g) a pair of screeding and anchoring angles, each of said pair of screeding and anchoring angles including first and second leg portions extending in perpendicular relation to each other, said first leg portion of each of said pair of screeding and anchoring angles being supported in juxtaposed relation to one of said first leg portions of said pair of cover support angles; and

(h) a pair of elongated finish angles supported on said second leg portions of said pair of screeding and anchoring angles and one of said plurality of cover plates when said one of said plurality of cover plates is in said finish position.

6. An elbow assembly for use in a trench header duct system comprising:

(a) a base plate;

(b) a plurality of corner posts fixedly secured to said base plate;

(c) a pair of wall angles, each of said pair of wall angles having first and second leg portions extending in perpendicular relation to each other;

(d) first means detachably securing said first leg portions of said pair of wall angles to said base plate with said second leg portions of said pair of wall angles extending in perpendicular relation relative to each other;

(e) a pair of cover support angles, each of said pair of cover support angles having first and second leg portions extending in perpendicular relation to each other;

(f) a pair of screeding and anchoring angles, each of said pair of screeding and anchoring angles including first and second leg portions extending in perpendicular relation to each other; and

(g) second means supporting said first leg portion of each of said pair of cover support angles in juxtaposed relation to one of said second leg portions of said pair of wall angles and said first leg portion of said pair of screeding and anchoring angles in juxtaposed relation to one of said first leg portions of said pair of cover support angles.

7. An elbow assembly for use in a trench header duct system as set forth in claim 6 wherein said second supporting means includes adjustment means for individual- 1y adjusting said pair of cover support angles relative to said pair of wall angles.

8'. An up-elbow assembly for use in a trench header duct system comprising:

( a bottom plate;

(b) an end angle having first and second leg portions extending in perpendicular relation to each other;

(e) first means fixedly securing said first leg portion of said end angle to said bottom plate;

(d) an elongated flat end plate;

(e) second means supporting said elongated flat end plate in juxtaposed relation to said second leg portion of said end angle;

(f) a front angle having first and second leg portions extending in perpendicular relation to each other;

(g) a throat member having a side wall, a pair of opposed end walls, and a flange extending from each of said pair of opposed end walls in perpendicular relation to said side wall of said throat member;

(h) third means securing said side wall of said throat member to said elongated flat end plate; and

(i) fourth means securing said first leg portion of said front angle to said flange of each of said pair of opposed end walls of said throat member.

9. An up-elbow assembly for use in a trench header duct system as set forth in claim 8 wherein said second means supporting said elongated flat end plate includes adjustment means for adjusting said elongated flat end plate relative to said second leg portion of said end angle. I

10. An up-elbow assembly with cabinet riser and connection flange for use in a trench header duct system comprising:

(a) a bottom plate;

(b) an end angle having first and second leg portions extending in perpendicular relation to each other;

(c) first means fixedly securing said first leg portion of said end angle to said bottom plate;

(d) an elongated flat end plate;

(e) second means supporting said elongated fiat end plate in juxtaposed relation to said second leg portion of said end angle;

(f) a front angle having first and second leg portions extending in perpendicular relation to each other;

(g) a throat member having a side wall, a pair of opposed end walls, and a flange extending from each of said pair of opposed end walls in perpendicular relato said side wall of said throat member;

(h) third means securing said side wall of said throat member to said elongated flat end plate;

(i) fourth means securing said first leg portion of said front angle to said flange of each of said pair of opposed end walls of said throat member;

(-j) a cabinet riser having a side wall, a pair of opposed end walls, and a flange extending from each of said pair of opposed end walls in perpendicular relation to said side wall of said cabinet riser;

(k) an elongated flat riser front member;

(1) fifth means securing said elongated flat riser front member to said flange of each of said pair of opposed end walls of said cabinet riser;

(m) a connection flange means having a plurality of side walls and a flange portion extending outwardly from each of said plurality of side walls; I

(n) sixth means securing said connection flange means to said cabinet riser; and

(0) said cabinet member being mounted on said throat member in frictional engagement therewith.

11. An up-elbow assembly with cabinet riser and connection flange for use in a trench header duct system as set forth in claim 10 wherein said second means supporting said elongated flat end plate includes adjustment means for adjusting said elongated flat end plate relative to said second leg portion of said end angle.

12. A trench header duct with expansion joint for use in a trench header duct system comprising:

(a) an elongated duct trough having a base and a pair of opposed side walls extending outwardly from said base in perpendicular relation thereto;

(b) a pair of cover support angles, each of said pair of cover support angles including first and second leg portions extending in perpendicular relation to each other;

(e) a pair of screeding and anchoring angles, each of said pair of screeding and anchoring angles including first and second leg portions extending in perpendicular relation to each other;

((1) first means supporting said first leg portion of each of said pair of cover support angles in juxtaposed relation to one of said pair of opposed side walls of said duct trough and said first leg portion of each of said pair of screeding and anchoring angles in juxtaposed relation to one of said first leg portions of said pair of cover support angles;

(e) a plurality of cover plates, each of said plurality of cover plates having a flat portion and trim portion mounted along at least two edges of said fiat portion in perpendicular relation thereto;

(f) second means supporting said plurality of cover plates on said second leg portions of said pair of cover support angles wherein each of said plurality of cover plates is invertible between a screeding position wherein said trim portions are in abutting relation With said second leg portions of said pair of cover support angles and a finished position wherein said trim portions extend outwardly away from said second leg portions of said pair of cover support angles; 4

(g) a bottom pan having a base and a pair of spaced side walls extending outwardly therefrom in perpendicular relation thereto;

(h) a pair of side angles, each of said pair of side angles having first and second leg portions extending in perpendicular relation to each other;

(i) third means supporting said first leg portion of each of said pair of side angles in juxtaposed relation to one of said side walls of said bottom pan;

(j) aflat elongated cover;

(k) fourth means securing said fiat elongated cover 18 to said second leg portions of said pair of side angles; and (1) said bottom pan being partially inserted into said duct trough and being retained therein by means of frictional engagement therewith.

13. A trench header duct with expansion joint for use in a trench header duct system as set forth in claim 12 wherein:

(a) said first supporting means includes first adjustment means for individually adjusting said pair of cover support angles relative to said pair of opposed side walls of said duct trough;

(b) said second supporting means includes second adjustment means for individually adjusting each of said plurality of cover plates relative to said pair of cover support angles; and

(c) said third supporting means includes third adjustment means for individually adjusting said pair of side angles relative to said spaced pair of side Walls of said bottom pan.

References Cited UNITED STATES PATENTS 2,849,942 9/1958 Goemann 52-220 X 3,023,032 2/1962 Johnston et al. 2-85-424 X 3,061,663 10/1962 Reiland 52-221 X 3,074,208 1/1963 Seidel 52-221 3,196,764 7/1965 Grieder 174-48 X 3,204,378 9/1965 Stuessel et al. 52-221 3,435,568 4/1969 Hoseason et al. 52-221 FOREIGN PATENTS 771,877 11/1967 Canada.

424,842 2/ 1935 Great Britain.

901,279 7/1962 Great Britain.

ALFRED C. PERHAM, Primary Examiner U.S. Cl. X.R. 

